Propellent powder



Patented Jan. 14, 1941 PROPELLENT POWDER Ellsworth S. Goodyear, Kenvil, N. .l'., assignor to Hercules Powder Company, Wilmington, Deh, a

corporation of Delaware No Drawing. Application December 13, 1939,

Serial No. 309,041

7 Claims.

This invention relates to an improved propellent powder for ordnance field pieces, and more particularly to 'a propellent powder which is smokeless, flashless and non-hygroscopic.

The ordnance art for many years used black powder in all field pieces and were severely hampered because black powder produced large volumes of smoke and caused very bad fouling of the barrel whenever a shot was fired. To improve this condition a nitrocellulose powder was developed which reduced the smoke and fouling. This nitrocellulose powder was a great improve ment over black powder but did not give perfect results because, although nitrocellulose does not" give the smoke or fouling attending black powder, there is a very noticeable flash attending each shot. It was desirable to completely eliminate the flash attending each shot. It was also desirable to produce powders which would be resisitant to moisture but the black powders and nitrocellulose powders were hygroscopic.

The ballistics which were obtained with the various nitrocellulose powders did not present major difliculties as it was possible to obtain the desirable bullet velocities and breech pressures with comparative case. But the performance of these powders with regard to flash, and smoke produced and their inability to resist moisture were serious handicaps to eflicient operations and uniform performance.

The problem of flash is a major problem to the ordnance art as the flash developed by a gun provides the enemy with a method of accurately locating the position of the piece. The flash is easily noticeable by direct ground observation or byiaerial reconnaissance, and results in enemy .fire which may eiiectively destroy a battery of guns.

In a similar manner the smoke which is produced at each shot is objectionable since it allows the enemy to locate a battery of guns with comparative ease in daytime. The production of smoke upon firing around is further disadvantageous because it obscures the vision. of the gun crew and prevents accurate firing.

In addition to preventing smoke and flashing the powder which is most desirable should also be non-hygroscopic as moisture adversely affects the ballistics of the powder and results in nonuniform ranges forindividual shots. Thus, there have been many attempts to produce a powder which will be smokeless, flashless, and non-hygroscopic whilestill giving the ballistics desired.

These three problems, flashing, smoke, and hygroscopicity, have resulted in a great deal of expensive research in attempting to find a method of producing a powder which is satisfactory for use in present day military operations.

There are at present a few smokeless powder formulations which are classed as flashless and non-hygroscopic, but these powders, while the best .known to the art, are not entirely satisfactory since they require the addition of two or more ingredients to the nitrocellulose to obtain 10 the proper ballistics and the desired flashlessness, smokelessness, and non-hygroscoplcity. These types of powders are illustrated by U. S. Patent 1,854,776 which requires the addition of both an oxygen deficient and an oxygen carrying compound in the proper proportions to give the de= s'ired'results. Such double additions are diflicult to control, make the powder more expensive, and causes difliculties in obtaining the ballistics desired.

The various powders now in use due to the variety of ingredients have higher charge weights for given ballistics than powders that do, not contain ingredients for reducing flash, smoke and hygroscopicity. An economic problem is thus introduced when attempting to produce a new powder that has" the desired characteristics, due to the plurality of ingredients.

An object of this invention is to prepare a prov pellent powder which is smokeless, flashless, and non-hygroscopic.

A further object of this invention is to produce I a propellent powderfor use in field pieces which produces the desired ballistics without causing flashing.

A still further object of this invention is to produce a propellent powder which will give the desired ballistics with reduced charge weights.

Other objects will be apparent hereinafter.

These objects may be accomplished in'general by colloiding a mixture of nitrocellulose anddinitrotoluene, pressing the colloid into strands, and granulating to the desired grain size. The colloid may contain a small amount of diphenylamine or other equivalent compounds to act as a stabilizer for the nitrocellulose.

. Thus, in accordance with this invention, .1 have found that I may by using dinitrotoluene in conjunction with nitrocellulose produce a smokeless propellent powder that is flashless and nonhygroscopic. The percentage of dinitrotoluene which I use in my powder must be controlled in a very close range as I have found that less than about 21% of dinitrotolueziesvill allow the powder to flash while more than about 24% dinitm;

toluene causes the powder to produce undesired volumes of smoke. Therefore, the powder composition which I have found to be smokeless, fiashless, and non-hygroscopic consists of an admixture of about 21% to about 24% dinitro'-' toluene and about 76% to about 79% nitrocellulose. This admixture will also contain about 1% by weight of a nitrocellulose stabilizer such as diphenylamine, the stabilizer which is normally added to all nitrocellulose powders to react with any decomposition products formed by the nitrocellulose in storage.

In manufacturing the powder of my invention, I have found that the nitrogen content of the nitrocellulose will affect the ballistics and hygroscopicity of the powder produced and I have found that the most desirable powder is produced when the nitrogen content of the nitrocellulose is above about 13% and preferably is about 13.2%.

Specific examples of the method of manufacturing the propellent powder of my invention and the results obtained by its use are as follows:

EXAMPLE 1 There were mixed in 2. Werner and Pfieiderer mixer 152 pounds of nitrocotton having an average nitrogen content of 13.21% with 46 pounds of 1, 2, 4, DNT, 2 pounds of diphenylamine, 47 pounds of alcohol and 43'pounds of acetone. This powder after proper mixing was blocked to cause further colloiding and then pressed in the usual smokeless powder press through a die .140" in diameter and having seven perforation pins .020" in diameter. The strands of powder were cut into four pellets per inch by using a Carney Point cutting machine. After the cutting operation, the powder grains were water dried for 3 days at 50-55 C. and then air dried for 3 days at 55 C. The finished dried powder had a mean web of .0154 inch. Its hygrosdopicity was 0.84% which is lower than that of most known powders. Hygroscopicity is determined by the standard U. S. Government methods. This improved powder made as above when tested in the 75 mm. gun model 1897 with a 12.37 pound projectile, and a 20.95 oz. charge gave a mean muzzle velocity of 1802 f. s. with 29,030 pounds per sq. in. pressure. After one year's storage at 50 C., the same charge of this powder gave identical velocity with a pressure of 29,660 pounds. No muzzle flash or smoke were observed in the test.

EXAMPLE 2 With 304pounds of nitrocotton having an average nitrogen content of 13.22%, were mixed 92 pounds of 1, 2, 4, DNT, 4 pounds of diphenylamine, pounds of alcohol, and 64 pounds of acetone. This powder was mixed in the usual manner, blocked, macaronied, reblocked, and pressed through a die .207" in diameter having 7 pins .0 8" in diameter and the resulting strand EXAMPLE 3 There were mixed 39 pounds dry weight of nitrocotton, 10 lbs. of liquid DNT, /2 lb. of diphenylamine, 10 lbs. of alcohol, 26 lbs. of ether,

and 2 /2 lbs. of acetone in the usual W 8: P mixer and when the colloiding was complete the powder mixture was pressed through a. .085-.020 single pin die and the resulting strands out four cuts to the inch. The powder grains were given five days water drying followed by three days air drying. There was no preliminary air drying or solvent recovery. This powder was tested in the mm. model 1897 gun with the 11.72 lb. projectile with a charge of 20.6 ounces which gave a velocity of 1809 f. s. with 25,480 pounds pressure. This powder contains only 20% dinitrotoluene and the results were not satisfactory as the powder, when tested as described above while smokeless and non-hygroscopic, flashed in a number of the shots made.

EXAMPLE 4 Nitrocotton dry weight 152 lbs., liquid DNT 46 lbs., diphenylamine 2 lbs., alcohol 42 lbs., ether lbs., and acetone '10 lbs. This powder was finished in exactly the same manner as in the previous example. When tested in the 75 mm. model 1897 under the same conditions as the previous example, this powder required 21 oz. to give 1805 f. s. velocity with 24,100 lbs. pressure. No flash was noticed on any shot in tests which used a 16 oz. charge or a 21 oz. charge of powder.

In the above examples I have used as solvent the ether-alcohol, an ether-alcohol-acetone, or an alcohol-acetone mixture which is not usually accepted as possible in the manufacture of known single base smokeless powders. 1

From the above examples, itis noted that the powders produced are flashless, smokeless and non-hygroscopic and give the desired ballistics in the guns tested.

In order to show the superior performance of the powder of my invention, a comparison is given in the following table between the powder of this invention anda standard Government powder. It will be noted that when the charge weights are the same, the breech pressure is lower for thesame velocity and when the pressures are kept constant, the velocity desired is obtained with a lower charge of powder.

TABLE 1 155 mm. gun

a -4 5 c 7 s lb. slug. 95 lb. slug. 951b. slug. 95 lb. slug. 95 lb. slug. 95 lb. slug. Powder #1. Powder #2. Powder #1. Powder #2 Powder #1. Powder #2.

24.171135". 24.78 lbs--- 24.17 lbs 24.181175" 24.17 lbs... 24.6 lbs. 2,400 2,400 2,381 2,381 2,386 2,386. Pressure 28,000..-" ,500. 28, 600.--" 28,200-.-.. 29,200"--. 29,000.

Powder i l-Government approved powder. Powder #2-Powder of my invention.

Powder til-Government approved powder. Powder 2Powder of my invention.

From the above tables the advantage of my powder in lower charge weight for desired balllstics when used in field pieces is brought out and also the advantage of maintaining low breech pressures with the same velocity is definitely shown. This powder further has the advantage of being economical to produce since there are only three ingredients necessary, to wit, nitrocellulose, dinitrotoluene and diphenylamine. In production, my powder is very easy to work, the pressing and cutting qualities being excellent. The cut grains are very smooth and regular and shrink in the normal manner to a uniform size.

To show the improvement in hygroscopicity which is efiected by the use of my powder, the results or tests on various samples are listed below in Table 6r TABLE 2 155 mm. howitzer 951b. slug. lb. slug 05 lb. slug- 9510. slug- 95l b.Mk.I 05 lb. Mk. I.

Powder#2 Powderi l. Powder. Powder-#1..- Powder #2. 7.9lbs--. 8.1 lbs--- 170105---- s.10 lbs 8.101b8. 1,484 1,470 1, 1,471 1,471. Pressure 28,200----- 27,800-...- 29, 28,700.

, v Powder #1-G0ve1'nment approved powder. Powder #2-Powder of my invention.

TABLE 3 75 mm. pack howitzer Test 1 2 a 4 I 5 0 Pro]ectile 14.710. Mk. 11. 14.710. Mk. 11. 14.7111. Mk. II. 14.7lb.Mk'.II 14.7111. Mk. '11. 14.7111. Mk. II. Powder Powderefl Powderfl Powder 1.-..-. Powderfl Powder #1 Powderfl. Charge 5 "M 5.6 M 15.55 M 14.7 M 15.55 7 13.9 01.. Velocity 001 001 1,224- 1,224- 1,217 1,217. Pressure-...- 4,000-- 4,000 19,100 21,300 18,800. 24,700.

Powder t l-Government 2 proved powder. Powder #2-Powder 01 my vention.

TABLE 4 TABLE 6 105 mm. anti-aircraft Powder Hygroscopioity Percent Test 1 z 3 4 Table l-Test 4 0.71 v Table 1Test 6.-- 0.65 V Table 2-Test 2--- 0.31 Proiectile 33lb.elug szlb'; slug- 33lb.'elug.- 33lb.elug. iTflblezJlwfl-n Powder Powderitl. Powderitil. Powderitl. Powder-#2. ,TflbleFTeSW-n 0.84 Charge 10.781bs..- 10.21 10.751115... 11.21115. Standard p Velocity. 2,800 2,800 2,800 2,800. 1- Pressure 33,150"-.- 32,000"--- 32,200"--- 28,000. 1.07 a 1.08

Powder #1-Govornment agproved powder. Powder 2-Powder oimy vention. 'Ihe powder is more economical than any of the known powders due to the reduced charges TABLE 5 needed to obtain the desired ballistics, and due to the possibility of using alcohol-acetone mixanti aircmft tures as the solvent. The flashless, smokeless, and non-hygroscopic qualities are such that this powder has passed all ordnance tests. Test 1 2 It will be understood that the details and examples hereinbefore set forth are illustrative i zmj ct ua g z lg sg gg wa s gsonly, and that the invention as broadly described 4'43 and claimed, is in no way limited thereby. Velocity 2. 8- What I claim nd sir Pressure 32,300. 31,000. a t a de 6 to protect Letters 1. A propellent powder consisting essentially of nitrocellulose within the range of about 76% to about 79%, dinitrotoluene within the range of about 21% to about 24%, and diphenylamine within the range of about 0.8% to about 1.2%, said powder characterized by being smokeless and flashless.

2. A propellent powder consisting essentially of nitrocellulose within the range of about 76% to about 79%, dinitrotoluene within the range of about 21% to about 24%, and nitrocellulose stabilizer within the range of about 0.8% to about 1.2%, said powder characterized by being smokeless and flashless.

3. A propellent powder consisting essentially of nitrocellulose, having a nitrogen content of at 6. A propellent powder consisting essentially of 77 parts by weight of nitrocellulose having about 13.2% nitrogen content, 23 parts by weight of dinitrotoluene and 1 part by weight of diphenylamine.

'7. A propellent powder consisting essentially of nitrocellulose having a nitrogen content of at least 13%, within the range of about 76% to about 79%, dinitrotoluene within the range of about to about 24%, and nitrocellulose stabilizer within the range of about 0.8% to about 1.2%, said powder characterized by being smokeless, flashless, and non-hygroscopic.

ELLSWORTH S; GOODYEAR. 

